Amplifier for electromagnets



Dec, 18 1923.

F. SCHROTER AMPLIFIER FOR ELECTROMAGNETS Original Filed March 16. 1921 Patented Dec. 18,- 1923.

UNITED STATES rnrrz sonnornn, or BERLIN, GERMANY.

AMPLIFIER FOR ELECTROMAGNETS.

Application filed March 16, 1921, Serial No. 452,823.

To all whom it may concern:

Be it known that I, Fru'rz Sormi'mm, a citizen of the German Republic, and a resident of Berlin, Germany, have invented an Improvement in Amplifiers for Electromagnets (for which I have filed an application in Germany, No, 36,160, Nov. 9, 1917), of.

which the following is a specification.

This invention relates generally to amplifiers and more particularly to an amplifier for multiplyin or increasing the effects of current and V0 tage changes in electric circuits.

One of the objects of this invention is to provide a simple and practical amplifier that may be readily incor orated in an electric circuit and that will e of effective and reliable action.

This invention aims also to provide an amplifier of the above character for readily detecting and making efi'ective changes in voltage or current in an electric circuit without necessitating the employment of an auxiliary or extraneous source of potential.

Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, arrangement of parts, and combination of/ elements as will be exemplified in the structure hereinafter described and shown in the accompanying drawing and the scope of the application which will be indicated in the following claims.

In the drawings, the single figure is a diagrammatic representation of a preferred embodiment of this invention, showing the several elements of the amplifier and the preferred electrical relations thereof.

Referring to the drawing there is shown connected across the conductors 10 and 11 of an electrical circuit a pair of coils 12 and 13 wound upon or associated with a core 14 of an suitable magnetic material and so woun with respect to one another that coil 13 opposes the action of coil 12, or, in other words, that the action of the two coils is differential. The coils 12 and 13 associated with the core 14 constitute an electro-magnetic device whose resultant action may be made use of in operating any suitable devices by such means as, for example, an armature 15 suitably pivoted in proximity to the core 14 and adapted to be operated upon thereby. Connected in shunt with the Renewed lay Q, 1928.

coil 12 is a glow discharge tube 16 Whose electrodes 17 and 18 are connected respectively to the terminals of the coil 12.

The tube 16 is of the type containing an atmosphere of gases of the helium group at low pressure and having electrodes 17 and 18 made preferably of metals of the alkali group or alloys thereof, or of any other suitable metal. Gases such as argon, neon and others of the helium roup, are found to function advantageouiy in a tube of this type but mixtures of these gases with other gases, such as with hydrogen for example,

'may also be employed. Tubes of this character have been found to permit the passage of an electric current therethrough at usual or common voltages, such as 110 volts for example, without necessitating an auxiliary arrangement for increasing the terminal voltage to start the discharge from one electrode tothe other. If the electrodes are made of materials as above mentioned, the size and arrangement of the electrodes with respect to one another are properly designed,

and the gaseous content chosen as above described, it is possible to give the tube 11. voltage-current characteristic which has a substantial portion thereof substantially parallel to the current axis. A tube of such a voltage-current characteristic will, therefore, maintain a substantially constant voltage at its terminals throughout material changes in current therethrough, the part. of the characteristic chosen for operation herein being the substantially flat portion parallel to the current axis. The tube 16 is operated on that portion of its characteristic above pointed out, wherein material changes in current result in only immaterial or practically no chlanges in the terminal voltage across the tu e.

Thus in the circuit arrangement hereinbefore described, the tube 16 in maintaining a substantially constant potential across its terminals during current changes through it will also maintain a constant potential across the coil 12 so that the electro-mag- 'netic effect of the latter, and therefore its differential action upon coil 13, will be maintained practicall constant. The coil 13 be ing in series wit the tube 16, however, will respond toall current changes to which the tube 16 is subjected and which may be caused by changes or fluctuations in the voltage across the conductors 10 and 11 by.rea-'j Ill iii

son, for example, of changes in the load in the circuit of which the conductors 10 and 11 form a part.

Since the potential across the Winding 12 is thus maintained constant, the current through the winding and hence its ampereturns will be maintained constant and will efi'ect a constant counter-magneto-motive force opposing the winding 13. Assuming for example that the winding 12 normally has a diderential action equivalent to 900 counter-ampere-turns and assuming further that as a result of the fluctuations in the circuit voltage impressed upon the conductors 10 and 11, the ampere-turns of Winding 13 are equivalent to 1000 in one in stance and by reason of a further momentary change become equivalent to 950 ampere-turns, the resultant change in the net ampere-turns of the tWo windings vwill be from 100 to 50 or 50%, the latter change of 50% being suiiicient to operate the armature 15 associated with the core 145. To produce the changes in the ampere-turns of the wind ing 13 as above assumed from 1000 to 950, a change of 5%, which corresponds to a voltage change across the conductors 10 and 11 of 5%, is requisite, which change however is insuihcient to bring about a sensitive and reliable operation of a device such as a re-.

lay, for example, it connected directly across the conductors. By means of the arrangement of the elements above described, however, this change in voltage of 5% is thus made to efiect a change in resultant magnetic motive force of 50%, sufficient to cause a positive and sensitive action of the relay windings.

The elements ot' the tube 16 and hence its voltage-current characteristic may be so determined that instead of maintaining a constant terminal voltage, the terminal voltage of the tube may be made to decrease as the current through the tube increases. A tube of such characteristics will greatly increase the sensitiveness of the amplifier hereinbetore described, since an increase in the current through the tube 16 will result in av like increase in the ampere-turns oi the Winding 13 accompanied by a simultaneous decrease in the ampere turns ot the Winding 12 act ing in opposition to the winding 13. By this arrangement the net ampere-turns available for operating upon the armature 15 be increased for given change in potential across the conductors 10 and 11 and the sensitiveness of the amplifier increased.

/llhile in the embodiment hereinbetore ole-- scribed an armature 15 is illustrated as re- "v g to the net or resultant magnetomotive-icrce of the windings, it will be untood that any other suitable means may -1 ployed will be responsive to the in the net thin of the differential her-agrees it will be noted that there has been provided in this invention an amplifier wherein a slight or small change in the circuit voltage, of itself insutiicient to bring about the effective operation of a suitable mechanism intended to respond as a function of the initial change, is multiplied to such an extent that the positive operation and response of the relay, for example, is assured. Such an amplifier as has been hereinbetore described may find various applications, and as an example of such an application it may be noted that the amplifier may be advantageously employed as the governing element intended to respond to voltage changes in a main circuit of a voltage regulator, the armature 15 being provided with suitable contacts for closing or opening the circuit to the main voltage regulating element which may be of any desired construction.

As many possible embodiments may be made of the above invention and as various changes might be madein the embodiment above set forth, it is to be understood that all matter herein set forth is to be interpreted as illustrative and not in a limiting sense.

ll claim as my invention:

1. In apparatus of the class described, in combination, an electric circuit subjected to variations in potential, a pair of (litterential windings connected in series across the said circuit, and means connected in parallel with one of said windings for maintaining constant voltage across the terminals of said winding.

2. ln apparatus of the class described, in combination, a main electric circuit subjected to fluctuations in potential, a series circuit connected across said main circuit comprising a coil and a device adapted to maintain a constant voltage at its terminals throughout fluctuations in current therethrough and through said coil in response to fluctuations in potential of said main circuit, and a coil connected across the terminals of said device and Wound to oppose the action of said first coil.

3.1m apparatus of the class described, in combination, a main electric circuit subjected to fluctuations in potential, an electromagnetic device connected across said circuit and subject to variations in current due to said potential fluctuations, means in series with said electromagnetic device adapted to maintain at its terminals a constant Ht drop throughout said variations in current, and an additional electromagnetic device connected across the terminals of said means and adapted to oppose the action of said first electromagnetic device.

4-. in apparatus oi? the class descrihed, in combination, a main elec ic subjected to ictuations in voltage, a relay having one co ou ed across circuit and responsive to variations in current due to said fluctuations in potential, an opposing Winding associated with said first mentioned winding and means connected across the terminals of said opposing winding for maintaining a constant potential across said winding.

m5. In apparatus of the class described, in combination, a main electric circuit subjected to fluctuations in voltagepa series circuit connected across said main circuit comprising a relay winding and a gaseous conduction tube, said circuit being subjected to variations in current due to said voltage fluctuations and said tube being adapted to maintain a constant terminal voltage for variations in current therethrough. and a differential winding opposing the action of said relay winding, said differential winding being connected across the terminals of said tube.

6. In apparatus of the class described, in combination, a main electric circuit sub jected to fluctuations in voltage, a series circuit connected across said main circuit and comprising a pair of differential windings of a relay and a gaseous conduction tube adapted-to maintain a constant terminal voltage for variations in current therethrough due to said fluctuations in voltage connected across one of said windings.

7. In apparatus of the class described, in combination, a main electric circuit subject to fluctuations in voltage, a relay having two opposed windings asociated with sive to the voltage fluctuations of said main circuit, and means associated with the other of said coils for maintaining a constant current therethrough to permit said coil to maintain a constant differential action with respect to said first mentioned coil.

9. In apparatus of the class described, in combination, an electric circuit, a pair of differ ntial windings, one of which is con-.

nectet to said circuit to be responsive to fluctuations that take place therein and the other of which is connected to said circuit to receive energizing current therefrom, and means connected with said lastmcntioned winding adapted to prevent an increase of energizing current through said winding when fluctuations in said elec- 'tric circuit increase the excitation of said first-mentioned winding.

In testimony whereof, I have signed my name to this specification'this 22nd day of January, 192

DR. FRITZ SCHRCTER. 

